Outside these walls
by NellieRai
Summary: Tumblr Prompt: C/B are doctors and put the on-call room to good use.
1. Chapter 1

**Disclaimer: Not mine, I don't own Castle. **

**A/N: Clearly this is very AU. And very M rated. This was a prompt from tumblr but I didn't want to change the rating for Arbitrary and I had so much fun writing this one that I may expand on it. Not anytime soon but I'm posting it alone just in case. Since I put the prompt in the summary, I'll stick it here too just in case you clicked without reading the description.**

**Prompt:_ C/B are doctors and put the on-call room to good use._**

Pleasure zips up her spine, crawls through every limb and she's alive with it. Clawing at the thin uncomfortable lining of the cot. Her white coat is gone, her scrub pants are still trapped around an ankle but the only thing she's aware of is the man between her thighs. They do this now. They sneak off, they shouldn't. She doesn't even like him ninety percent of the time. But he's the one tearing her apart with just his mouth. He's the one licking and biting a slow path up her thigh.

She orders him around a lot. But right now, she can't. Not when his lips are hot against her. Not when her hips jerk hard when his tongue finds her clit. She's already close. He's too good at this. With his hands holding her in place, this might be the only time she fully appreciates that mouth of his.

Yeah. With one hand tugging his hair as she arches into him, she'll admit she likes his mouth. Her body enjoys his. They found that out weeks ago. After arguing for twenty minutes and realizing how horny she was, she hadn't been surprised when he'd trapped her against the wall and kissed her crazy.

But her reaction to him still stuns her silent. Even now, with her legs over his shoulders. Moans and sighs being all she can manage as he groans at her taste. Maybe his name slips out once or twice. Castle. Okay three times. Definitely three times in rapid succession when he slides his fingers through her folds and sucks hard. She's been soaked from the moment he asked when she could slip away for a moment. His voice low and husked in her ear. She knew what it meant. This is what they do. Quick and dirty meetings they pretend never happen.

He smiles against her pubic bone, nips his teeth into her flesh and she bucks against him. Her skin flushing with heat and her muscles clenching tight. He knows how to wind her up. He knows how to curl his fingers and make her spine bow. And she almost hates him for it. She wants to. She wants to hate him for how quickly he makes her orgasm, how hard he makes her come. Because she can't, she's too busy praising his ability for the tremble in her thighs and the way she's gulping air as if she can't get enough.

She bites her lip. Tries not to be too loud. But then he slips another finger inside to curl hard and presses his tongue flat against her and she's shattering. She doesn't know if she's loud, the blood rushes in her ears, her body tenses until her muscles ache. This man shreds her and gives her no time to recover. His fingers leaving her and maybe she whimpers at the loss but then he's gripping her hips. Lifting himself above her.

She's still mid orgasm, body buzzing, when he pushes into her. A long deep thrust. And when did he lose his pants?

It's his blue eyes she sees when hers fly open. When the low moan burns in her throat and echoes out around them. It's the scent of sex that mingles between them and then she's craning up to kiss him. To steal his lips with her own and hold them captive. He tastes of her, a heady dizzying taste that has her chasing when he tries to pull back. But he's mumbling, making it impossible for her to slide her tongue over his.

"Did you lock the door?" Did she? She thinks she did but she couldn't care less because he's thrusting. Filling her over and over. Pushing deep and her legs are still shaking. She's just come down from her high and he's already building her back up.

She cries out when his palm slides beneath her top, beneath her bra. He's unforgiving, almost as if angry at her. Groping her breast, making her hips slam up against his when his fingers tug at her nipple. And then he's shushing her, growling words at her.

"Quiet. You have to be quiet or we'll be caught."

She has to be quiet? He's ordering her. And part of her thrills in that, making her clench hard around his length. Then he's the one that can't keep it down but he's still chastising.

"Beckett. Seriously. Quiet. I know it's hard" he punctuates it with a thrust and then stills, "for you."

"Shut up and move, Doctor."

He does. He does and she's muffling her moans with his mouth. Slicking her tongue against his. Not understanding the possessive touch but reveling in it regardless. But she's a fast learner. Following his lead and sliding her hands up the back of his scrubs to cling, to feel his muscles flex and bunch.

She chases his body, needing every sharp thrust. This time when the spring wound tight between her hips unravels, he's right there too. Sloppy movements and the rumble vibrates through his chest. She sinks her teeth into his shoulder, digs her nails into his side.

He stills. She falls limp and his breathing is loud against her ear. This is when they untangle, when they stop touching and get dressed. This is when they slip out of the on-call room and pretend they didn't spend their downtime fucking each other's brains out.

But something is different this time. Because he doesn't move. His touch turns soft, his palms cradling instead of gripping. His fingers sliding gently up her ribs and she's about to push at his chest when she feels his lips press to her cheekbone. A fleeting brush that has her freezing. This isn't what they do. She doesn't know what he's doing.

It doesn't make sense. Not when he'd pinned her to the wall as soon as she joined him in here. Held her hands hostage with just one of his and had her pants down and his fingers between her thighs before she could choke out his name. He doesn't make any sense. They argue more than half the time they're in the same room. A 'who has the bigger dick' kinda competition and since she has seniority, she knows she wins.

She's the surgeon who's been here the longest. He's the newbie. The one that came in out of nowhere and turned her hospital, her home into his own personal playground. She doesn't like him. So why is her heart clenching when his mouth lingers on her cheek? Why hasn't she pushed him away yet?

And then he's whispering her name. Not Beckett. Not Doctor. Just Kate and they've never called each other by first name. Oh. She knows where this is going and she needs away. She doesn't do this. She also doesn't fuck other doctors in closets, stairways, the on-call room and yet she does it with him. This is her life, this hospital. She doesn't have room for anything. That's why he's convenient. Because she doesn't even like him.

Until her pulse jumps and her body whines at the loss of him when he pulls away. She ignores it, sits up as he searches for his pants. And she's straightening her bra and top when his palm reaches for her face.

"Cas-"

"We should do this outside these walls sometime." No they shouldn't but that's not what she says. She doesn't say anything, just meets his eyes and gets a little too lost in the blue. "Get a bite to eat maybe?"

"I don't think that's -"

"I saw you flirting with him. That other doctor."

"Davidson." And she swears he growls. "Castle, you and I? - we don't even like each other."

"We don't know each other."

"Exactly." She's reaching for her panties in a rush, knocking his hand away in the process. "Look, we have fun -"

"I like you. You're smart, you excel at what you do, I know you have a motorcycle because I've seen you leave. I want to know more."

"Are you saying that you were jealous?" She knows she hit a nerve when his jaw tightens. "Okay, okay. Maybe we can get a burger. I've been here twenty-seven hours. But I'm off tomor- no today. I'm off in a few hours."

"I do love a good cheeseburger."

She doesn't know why his smile makes her stomach flip or why she dresses a little more slowly. Until he's called away. His name being paged and she watches as he backs out of the room.

He's grinning at her, going on about burgers and she tries to warn him, tries to tell him but he's turning before she can. Smacking into the door as if he's forgotten it exists.

He unlocks it hastily, slips away with a look back at her. And he's adorable.

Shit. She's doomed. She likes him.


	2. Chapter 2

**Disclaimer: I don't own Castle. **

**A/N: This fic will eventually gain more chapters. This only got posted because Ris insisted and so I've spent a few days working on this chapter. I don't know when I'll add another but probably in a week or so. **

She's a little nervous and that's new. She's steady in her job, steady in her life. And now she's nervous because of a silly date with a man she's already had sex with. Multiple times. In a variety of places. But it's never been intimate. They've never talked much or lingered. Most of their conversations have been arguments. And now Kate Beckett is smiling at him as he holds the door to Remy's open for her.

She spent hours staring at her closet despite the place being casual. And she hates herself for that. And for the fact that she dressed up a little, dark jeans, purple silk top and she'd left her hair down, curled it. It's usually always up. She's thought of chopping it off and just hasn't yet. But tonight she has it down and added more makeup than she usually wears because it's a date.

Her stomach in knots because what the hell does she think she's doing? But he's attractive and she does kinda like him. Maybe. Okay, yes. Yes, she likes him. And she doesn't even know why. It just happened at some point. He's a little dorky and she doesn't know why she didn't notice that before. Probably because they were always partially naked and too busy gyrating against each other.

She picks the place to sit, doesn't really even ask his opinion on it and only realizes that the moment she's sliding into the booth. She sucks at dating. She's already failing miserably.

"Hope this is okay?"

"Perfect. My favorite spot." He's smiling as he says it but she doesn't believe him for a second. She does admire the casual look he's chosen. The black v-neck is a little distracting, she's probably staring. "So..."

He catches her, looks entirely too proud when her eyes dart up to meet with his.

"So?" It's awkward. What do you say to someone you have sex with all the time but never really talk to? Kate doesn't have the slightest idea and it seems like he doesn't either.

God this is horrible.

She's already itching for a way out. And she almost makes an excuse but then there's a waitress next to the table and the awkwardness just escalates.

"Hey, Rick!" A whole new level of uncomfortable coils in her stomach when she watches his face light up at the site of the young woman.

She's not the jealous type, she's not. And they aren't even together but she spits out her order wondering why she's the one sitting across from him and not the waitress that keeps giving him bedroom eyes. Because it's so obvious the woman likes him and Kate finds that while she's not jealous, she feels a little insulted. She's sitting right here. She could be his girlfriend and this woman is flirting right in front of her.

So maybe that's why she says it. Maybe that's why she opens her mouth as soon as they're alone again, maybe that's why she says the worst possible thing.

"Why aren't you dating her? She's into you and it didn't seem awkward with you two." _Like it is with us_ is what she wants to blurt out but she keeps that one silent, doesn't even give him time to reply before more stupidity tumbles out. "Is it because she's a waitress and younger?"

She doesn't even know where that came from. It's judgmental, it's rude and she watches the flash of anger cross his face. She expects an outburst, she deserves one. But he lets out a breath and he's calm when he speaks.

"Ouch. Just what kinda guy do you think I am, Beckett?"

"I uh, I'm sorry that...that was rude." And this is obviously a terrible mistake. "This isn't a good idea. I'm just...I'm gonna go."

She's a moron. Agreeing to a date with him was obviously a lapse in judgment. Probably due to the orgasms and what he can do with his mouth. But now she's embarrassed by her own behavior and it's not even his fault at all. It's her. All her. She doesn't know why she said that, why she even thought it or why there's a burning in her stomach at just the thought of the waitress returning. She knows she needs out and without anything more than an apology, she's fleeing. Standing quickly and almost sprinting out of the diner.

She sucks in air once outside, slows enough that she only ends up maybe ten steps away when she hears his voice. Right behind her. She should keep walking, just pretend she doesn't hear but he's right there. Warm fingers wrap around her elbow and she doesn't want to make a scene in the middle of the sidewalk. Of course he followed, of course he guides her over to the alley. This is the same man that confronted her in a supply closet when she tried to play off their first sexual encounter as a one time thing. And five minutes after, her pants had been off and she'd been pressed against a set of rickety shelves with him buried between her thighs and his tongue in her mouth.

This is a little different. She doubts he's about to challenge her on if she's aroused right now by mentioning shoving his hand down her pants to see if she's wet and she's not about to challenge him right back by telling him to find out.

But the look on his face isn't so different. He's determined. Just like he was then and she knows she'll give in. There's something there, beneath the awkwardness. She can feel it too and that's even more terrifying than her own behavior tonight.

He doesn't say a word for several seconds, he just stares at her and she finally relaxes and gestures for him to get on with it.

"Come back inside, you have to be hungry." She's starved but she shakes her head.

"I don't think -"

"Okay. If you don't want to eat there, then you pick a place. Somewhere you're comfortable."

"I just made an ass of myself and insulted you, why are you still insisting on a date?"

"Because I like you. And because you're nervous and I think a little jealous which is adorable." He smirks as he says it and she's struck with a lightning bolt of heat that electrifies every nerve.

This man is dangerous. And maybe right.

She doesn't give in right away. No, she makes him wait. Silence stretching for several long moments before she bites her lip and nods. If he wants a date even after her outburst then the least she can do is provide one. Maybe with a better apology later.

"Alright then. My place, we'll get takeout?" It comes out a question but she hadn't intended on it being one. He looks a little unsure and it makes her stomach twist in a knot.

_Why does he make her feel like this?_

"Okay. But I want dinner and not just -"

"No! No. We don't even have to...unless you _want_ -"

"How 'bout we just..." He gestures over his shoulder, his face contorted adorably from where their conversation was headed and she saves them both by pointing the opposite direction.

"I live that way." Even with the awkwardness lingering, she feels some of the nerves ease when he extends his arm. She loops hers through and feels the familiar jolt. Her body knows his, knows what he does to her and apparently craves him.

She's probably fucked. In more than one way. But it's more comfortable walking with him and talking about mindless things like other pedestrians or how long it takes for the crosswalk light to change than it had been to sit across from him in a diner. It melts away piece by piece and she's laughing at some joke he's made not even three blocks from where they started while ordering from a food truck.

* * *

Kate knows the moment she invites him into her apartment that they'll probably end up naked before this date is over but it doesn't send the same kind of panic through her body as just the thought of a simple dinner in public had. She doesn't know why. She doesn't even know what happened in their walk here or how it changed things but the nerves have settled. And though she does still feel like a bitch for saying certain things to him, that's not why she tells him to make himself comfortable.

She makes herself pull it together in the kitchen, tells herself that this is a date with an attractive, available, and fantastic-in-bed guy. And she does like him. Which is probably why this scares the living daylights out of her and makes her say stupid things. She grabs a couple of beers to go with their burgers and joins him in the living room.

He's already set up their food on the coffee table, but he hasn't started eating and she offers a small smile when she hands him the beer. Her couch is huge, a sectional that actually came with the place when she leased it but she chooses to sit right next to him instead of at the other end. They've been a helluva lot closer than side by side with their thighs brushing.

It still has a slow burn of arousal firing up in her abdomen and she hears his soft sigh. She's not the only one picturing how this will end. Even if sex hadn't been her intention when she asked him to come home with her.

He takes a bite first, breaks the unease and she follows by scarfing down a couple fries. It isn't nearly as uncomfortable anymore and she feels confident enough in her own space to tuck her legs beneath her and turn in towards him. This time, she's the one to start talking.

"These probably aren't as good as Remy's, I'm sorry. We could have asked for it to-go I guess."

"Not as good, no, but we can always go back eventually." He shrugs as he says it, plays it off like he isn't suggesting they have a future.

But he is. She catches it in the slight grimace. He's kicking himself for mentioning it and she swallows the bite she took, picks invisible crumbs from her purple top. It takes a few seconds before she can look up at him but when she does, she just gives in.

"I like you and we have fantastic sex." He grins and she mirrors it. "I'm sorry about earlier, I barely know anything about you but I want to know more too."

"Then let's start with how your day went."

"I slept all day so probably not the best conversation starter. Why did you transfer hospitals?"

"Let's not talk about work. When I'm not there, I enjoy not thinking about it." He has a point so she drops it easily, and takes a bite of food. "I know you're a native New Yorker, so I won't bother asking where you grew up. Those are boring questions anyway."

"Boring?"

"Definitely. I prefer figuring it out, paying attention to the little details. You're Manhattan through and through."

"Okay, my turn." She pauses a moment to study him, to tilt her head and raise a brow when he takes a big bite of his cheeseburger. "You're a native too so I won't even go there, though I'm mildly impressed. You're incredibly skilled in what you do but make a lot of choices based on your feelings and not necessarily on what the outcome will be. You lead with your heart. I admire that."

"You fight me on it regularly." If he didn't sound amused she'd be getting defensive. But he's nudging her knee with his own and she nudges back.

"Someone has to keep you in line." And she won't say it but she honestly could not stand him when he first arrived. He came off as an ass.

Not so much right now. Right now he's softer, not so cocky. Yeah, she likes him.

"You like to read." He pops a fry in his mouth after he says it and she frowns for a moment until he points and then she feels like an idiot. She has bookshelves and there are random books littered around. Of course he noticed. It's hard not to. "Something we have in common. Favorite genre?"

"You don't want to guess?"

"I could. But then I'm doing all the talking and I didn't ask you out to listen to my own voice."

But she could listen to it all night. Just the thought of it has a shiver racing down her spine.

"I like mysteries. And I like good sci-fi too. You?"

"Mystery, sci-fi, comics, graphic novels, horror but only sometimes or my daughter says -"

"You have a daughter?" That's something she should have known, something she should have asked probably but then again maybe not. She's been out of the dating game too long.

And the thought of him being responsible for a small human has her biting her lip, her body flushing in a new crashing wave of arousal. Because now she can see it, him being a father. She should be scared, she should be shoving him out the door and instead she scoots closer.

"Yeah, her name is Alexis. She's twelve going on forty."

"I..." She doesn't know what to say. She really doesn't and she feels bad because something darkens in his eyes.

"If that's a deal breaker for whatever this is -"

"No. It's not." That's what scares her. "So she's almost in her teens?"

"Don't remind me. I'm not ready."

"Does she live with...nevermind, that's none of my business." But she wants to know. Her curiosity is piqued.

"Me. Her mom isn't really big into being a mother." He's not looking at her now, those blue eyes focused on his food as he picks through his fries and Kate reaches for his hand before she can think twice.

"Castle, I was serious. I'm not about to make you leave just because you're a father." She's never held his hand. Not unless guiding it over some part of her naked skin counts and when she twines her fingers with his, she's pretty sure it doesn't. "In fact, I think I like you a little more."

"Did I mention I also have a dog?" He's joking, it's obvious in the way he squeezes her hand, in the way his eyes meet hers and in the vibrant flash of his smile.

She laughs because he's ridiculous. Because he's sweet. And maybe this isn't a mistake at all.

"So...you probably have to go home soon, since you have a kid." She hopes he hears the question, she's made it rather obvious.

"Actually, she's spending the night with my mother. Something about girl time and no boys allowed."

"Mm. That means boy talk, and things dads don't need to hear." The look on his face is priceless and exactly what she was going for. He pales, his food forgotten as he gapes at her.

There's a beat of silence, a moment she remembers how they agreed this wouldn't be about sex but there's something about him that she just can't resist. And they've agreed they like each other. So she places her food back on the table and then she crosses the line they'd drawn.

The second her mouth touches his, he's pulling her closer. She thinks his food hits the floor but she doesn't know or care because he's warm. His lips slide over hers, his arms wrap around her and she's in his lap before she can taste his gasp of her name. It's not about the sex, not this time but the heat between her thighs is raging just as it always does. Maybe a little more intensely now. If that's at all possible.

It's an urgent need. A swamp of want. She's drowning in it with every nip of his teeth, every slide of his tongue. And this is familiar. He's familiar and he's also grabbing her wrist and stopping her from pulling her own shirt off the second she tries. She's already impatient, growling his name and rocking her hips because the arousal has been lingering since she woke up knowing they had a date tonight. But then he's sliding her shirt up, slow, his fingertips hot on her skin as he trails them along behind.

He's methodical, unhurried. And it's so different from every time they've had sex that she's stunned still. Her eyes lock on his, only breaking away when he pulls the shirt over her head. Something shifts between them and she tries to gain the upper hand, tries to crush her mouth back to his because that's normal for them, it's safe.

He doesn't let her. He slows with a whisper.

"We have all night." Those words change everything, they force her to see that this isn't just about quick fucks with their clothes still mostly on. He intends to take his time.

And the sound she makes at just the thought of it, just the look in his eyes, is nothing more than a needy whine. She wants it. The promise he's making, she wants it.

This time, he's the one to kiss her. With a palm cupping her face and lips soft as silk against her own. She breaks it, just long enough press herself impossibly closer and give her reply.

"Take me to bed, Castle." She's barely got the words out before he's standing, making her wrap her legs around him, cling as he stumbles through her apartment.

He finds her room without needing directions and she's not sure she could've given them anyway. Not when he keeps pressing open mouthed kisses to her neck, sucking at her skin. She doesn't even know how they make it without crashing into something but they do. One minute she's clinging to him and the next he's urging her to stand on her own and stripping her slowly.

She feels nervous again. It's ridiculous because they've done this. Okay, they've never seen each other fully naked but they've seen the good parts and yet she's nervous. Growing wetter by the minute because watching him strip himself down is possibly the sexiest thing she's ever seen when he wont take his eyes off of her. The moment they're both bare, he's pressing against her, backing her toward the bed and she's more than willing to let him.

She shivers hard when he palms a breast and lowers his mouth to her nipple. Her legs give and he smirks into her flesh, bites just hard enough to have her sinking her teeth into her lip to stay quiet. They've always had to be quiet or risk getting caught.

But this is different and he tells her as much when he pulls away, when he guides her down on the mattress.

"You can be loud." Just those words and the fingers sliding between her thighs, parting her folds, pull the first moan from her.

It's soft, slow. A mirror of his ministrations. And then he's sipping from her lips while his thumb circles her clit, spreading her arousal and something deeper claws its way out of her throat.

She expects this, he's always so good with his hands but he barely touches, just lazy circles. And usually it's hard and fast and she's coming in seconds. Not this time. He's enjoying this. Around and around as she pants into his mouth and grinds against his hand for more pressure. The burn in her abdomen coils tight, building, her skin feels every brush of his. She needs more, she needs something.

"Castle," It's a low growl, and when he smirks, she bites his lip.

He plays her like a piano. Pressing, stroking, easing up when she's close and smearing her thighs with the evidence of her arousal every time he grips her to hold her in place. She's chanting by the time she feels him slide between her legs and rest heavy. He might have the upper hand but she's the one reaching down to wrap her fingers around his shaft, pull him closer.

He falters, his thumb stroking faster as she rocks up against him, chasing. Teasing herself by sliding his tip through her folds. And she's so close, so close that her abs tighten and the second he slowly pushes inside, she's breaking apart on a low moan. Both hands falling to grip the sheets as he slides deeper, her walls fluttering around him, clenching tight with every inch until he's flush against her and she can feel him hot and heavy inside.

It isn't a rushed fuck on borrowed time. It's deep kisses, moans, cries of pleasure when he hits just the right spot. Each thrust of his hips heightening her sensitivity, bringing her closer to the ecstasy her body is begging for. And it's there, burning in her blood, just beneath her skin. Ready to burst.

It's hot, boiling. Her skin sticking with his, sliding as the moisture pools between them. And she doesn't want slow anymore. The pressure is too much, too intense. Even with her mouth open against his, her lips and tongue begging for the relief. He never gives it. He drags it out until her spine bows and her body trembles. Until she's coming on a sob of his name. Her nails digging into his back as he pulls out, a whimper leaving her lips when he pushes back in.

He follows her over the edge. A few more thrusts and he's pressing deep, groaning in her ear as he spills inside her.

Neither of them move. Just another reminder of how different it is this time. Not just being fully naked but they have nowhere to be. Their bodies quaking, slick with sweat. And for once, she's not in a hurry to pull away. To get back out on the floor. Because this is her bed and she's comfortable here. She can ask him to leave...but she doesn't want him to. She doesn't want him to let go just yet.

He doesn't. He lingers and even when he rolls off of her, he doesn't leave the bed. She waits to see what his next move will be and the moment he reaches for her, she curls into him. They've never done this. Never cuddled after sex. But whatever they just did...did not count as just sex. She's used to fucking him. Quick and dirty. She's not used to this. Maybe she could get used to it though.

"That was -" He groans instead of completing his sentence with words and she buries her smile in his chest.

"Do you have somewhere to be or..."

"If you want me to leave I will, but if you don't tell me to get out of this bed right now then you're stuck with me for the night."

She's oddly okay with that. She's okay with him staying and that's new.


End file.
